There will only be one Inspector Morse . . . no one can step into John Thaw's shoes

To millions of fans he is and always will be the one and only Inspector Morse.

Now writer Colin Dexter has written a clause into his will to make sure no other actor can step into the brogues of John Thaw, who played the legendary, hard-drinking Oxford detective.

Apparently the author doesn’t want anybody to try to outdo Thaw, who played the curmudgeonly sleuth until two years before his death at the Wiltshire home he shared with wife Sheila Hancock in 2002, shortly after his 60th birthday and the day after signing a new contract with ITV.

“We never want to repeat what John has done,” said Dexter, 83, who created the popular character in 1975.

The TV series Inspector Morse ran from 1987 to 2000 and at its peak attracted more than 18 million viewers in the UK and millions more in 200 countries across the world. The character died from a heart attack in The Remorseful Day. “A lot of people connected with Morse didn’t want anyone coming along to say we will try and outdo dear old John,” the writer told the Independent newspaper.

“I said I’m not ever going to allow that, full stop,”

The clause came to light during a Radio Times interview with actor Shaun Evans, who plays a young Morse in prequel Endeavour.

Mr Evans, 34, said: “I know that the creator, Colin Dexter, has it in his will that no one else can play the part, which is as it should be.

“It’s not something that can go on and on. I really don’t think it will.”

But despite Mr Evans’ admiration for the actor, he did not look to Thaw for inspiration when he took the part of the young policeman before he became a senior Jaguar-driving, opera-loving CID officer with the Thames Valley Police.

“I listened a lot to Michael Palin, who was from the north, went to Oxford and who was alive at that time,” he explained. “That’s how I imagine Morse’s voice to be.”

The ITV drama, penned as a prequel to Inspector Morse, made its debut with a feature-length special in 2012 and has spawned two series.

The executive producer took four years to convince Mr Dexter to give his permission for the project.

Evans said that Scandinavian crime dramas such as The Killing and The Bridge had also left their mark on Endeavour.

“Audiences want a certain darkness now and you have to pay attention to that,” he said. “There’s no denying that this character is a bit of a loner and slightly out of joint with his time and place. That’s what I find endearing about him. And perhaps the audience does, too.

“The world doesn’t need another detective series, so we have to do something different with it. If you’re going to do a show that has already had a long life, you have to grab it and do something new. So that’s what we attempted and I feel we’ve largely succeeded.”